To make up for a deficiency, in the aspect of voice call, of an LTE (Long Term Evolution) network, in the prior art, within a range of overlapping coverage between the LTE network and a 2G (2-Generation Wireless Telephone Technology, LTE generation mobile phone communications technology specification)/3G (3rd-Generation, 3rd generation mobile communications technology) network, a voice service of a user of the LTE network is switched to the 2G/3G network by using a CSFB (Circuit Switched Fallback) technology, to improve voice call quality.
According to a CSFB switching method provided in the prior art, in a switching process, user equipment needs to initiate a CSFB switching request message to an LTE base station when initiating a voice service, the LTE base station delivers a connection manner and a frequency of a target 2G/3G base station to the user equipment according to the switching request message, and after detecting the target 2G/3G base station according to the connection manner and the frequency of the target 2G/3G base station, the user equipment connects to the target 2G/3G base station, so as to switch the voice service that is to be enabled from the LTE network to the 2G/3G network. After the voice service is ended, when the user equipment is in idle mode, the user equipment is switched back from the 2G/3G network to the previous LTE network.
However, when a voice service is switched by using the CSFB switching method, one case is that, when user equipment cannot detect a target 2G/3G base station, the user equipment repeatedly performs the detection until a target 2G/3G base station is detected, and then connects to the target 2G/3G base station. As a result, there is a relatively long delay when the voice service is initiated. The other case is that, when a target 2G/3G base station cannot be detected, the voice service is interrupted. In both cases, reliability of voice service switching is reduced.